F1 fans; if you could have 1 piece of an F1 car, what would it be?

I actually have the wheel and used tyre off a williams from the mid 90s..I bought it in the formula 1 shop in chester for quite a lot of money..It has the certificate to prove it is a genuine williams part but if you read the small print it tells you that the wheel never actually raced or qualified..it did 50 laps testing but doesnt say where...some may say its a pointless purchase but i wouldnt part with it for the world....If i could have any part off a formula 1 car ever it would have to be a turbo charger from a mclaren that senna used...